(a) Field of the Invention
The present invention relates to a method for acquiring the processing time of a wireless signal.
(b) Description of the Related Art
Uplink and downlink transmission and reception methods in a wireless environment are classified into a Frequency Division Duplex (hereinafter, referred to as “FDD”) scheme where uplink and downlink transmissions occur on different frequencies and a Time Division Duplex (hereinafter, referred to as “TDD”) where uplink and downlink transmissions occur at different times. The HSDPA (High Speed Downlink Packet Access) standard for FDD and TDD uses protocols, such as Hybrid Automatic Repeat Request (hereinafter, referred to as “HARQ”).
The HARQ scheme is divided into a synchronous HARQ scheme and an asynchronous HARQ scheme depending on a data packet retransmission time point. The synchronous HARQ is a scheme in which data is retransmitted at a time point known to a transmitter and a receiver. The asynchronous HARQ is a scheme in which a transmitter, e.g., a base station scheduler determines the retransmission time point of a retransmission data packet to retransmit the data packet.
Moreover, the HARQ may be divided into adaptive HARQ and may be classified into an adaptive HARQ and a non-adaptive HARQ according to transmission attributes such as a resource allocation, modulation scheme, size of a transport block, and the like. The adaptive HARQ is a scheme in which the transmission attributes used for retransmission are entirely or partially changed and transmitted according to a change in a channel state. The non-adaptive HARQ is a scheme in which the transmission attributes used for an initial transmission are continuously used regardless of a change in the channel state.
To reduce signaling overhead caused by a control signal, such as resource allocation information, it is effective to use a non-adaptive synchronous HARQ scheme in which a retransmission time point and the transmission attributes are not changed.
But, it may be effective to use an adaptive asynchronous HARQ scheme with a scheduling gain if signaling overhead is not taken into account.
According to the HARQ scheme, a receiver checks whether an error is detected by decoding a data packet received by a physical layer, and, if no error is detected, transmits an Acknowledgment (ACK) signal as a feedback signal to inform a transmitter about the successful reception of the data packet. However, if an error is detected in the received data packet, the receiver transmits a Negative Acknowledgment (NACK) signal as a feedback signal to inform the transmitter about the detection of an error in the data packet. Upon receiving the NACK signal, the transmitter may retransmit the data packet. At this point, if the receiver is a base station and the transmitter is a terminal, the terminal is allocated uplink transmission resources via a downlink control signal by using the allocated transmission resources.
In general, a wireless communication system uses a fixed transmission time point at the time of transmission and reception of a data packet and a control signal between a base station and a terminal, between base stations, or between terminals. This assumes that data transmission processing capability is the same for both a base station and a terminal. However, with the development of system technology and memory technology, data processing capability varies between a base station and a terminal, between terminals, and between base stations. For example, the data processing capability of terminal A may be more excellent than that of terminal B. In this way, a method of using a fixed transmission time point in a wireless communication system where a higher transmission rate can be satisfied may degrade transmission quality.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.